PURPOSE: To obtain a moisture absorbing and desorbing sheet having a large amount of water absorbed and desorbed and characteristics of high water vapor absorbing and desorbing rate.

CONSTITUTION: An acrylic acid containing a carboxyl group neutralized with a metal ion is mixed with at least one or more selected from (1) a polyalkylene glycol diacrylate, (2) a hydroxyalkyl acrylate and (3) an amine compound containing one or more (meth)acryloyl groups in the weight ratio of 99/1-25/75 to give a resin composition, which is polymerized and cross-linked by irradiation and supported on a sheet to give a moisture absorbing and desorbing sheet. This moisture absorbing and desorbing sheet is suitable for uses such as a water absorbing material for a humidifier, a water absorbing material for condensation, a separator for an air conditioning heat exchange, etc., and has a high industrial value.